alphabet = ['a','b','c','d','e']
print(alphabet[0:3])
print(alphabet[2:])
print(alphabet[:4])
print(alphabet[-3:])

for value in alphabet[-3:]:
    print(value)

# 复制列表
numbers = [1,2,3,4,5]
print(numbers)

copy_numbers = numbers[:]
print(copy_numbers)


numbers.append(6)
copy_numbers.append(7)

print(numbers)
print(copy_numbers)